Each manhole has been inspected and identified as having moderate to severe I&I at the chimney area of the manhole.

This is an ongoing project for 500 manholes, which began in August of 2017. Ring and covers were replaced before Raven 581 was applied to prevent I and I at the ring and chimney area. After installation 90-day inspections were conducted and had shown Raven 581 performing well.

In addition to preventing I and I, most of these manholes are in the road and Raven 581 is also excellent at combating the effects of loading in the road caused by vehicle traffic.